This proposal includes a request to purchase a Philips 40 LS transmission electron microscope (TEM) to replace a Philips 300 model which is not only 18 years old but also prone to frequent breakdowns. This equipment is greatly improved with many typical optional items that are standard such as a eucentric goniometer stage for tilting the specimen plus/minus 60 degrees in the column. In addition, the camera holds a larger number of plates that will increase productivity by requiring less frequent down time for developing plates and re-pumping the column. This new microscope will be used by a group of NIH funded scientists, composed mainly of the principal investigator and various colleagues at the University of California at Irvine. Projects that require TEM support from the principal investigators's laboratory include studies on the morphology of models of focal and genetic epilepsy and the analysis of neuronal circuitry in the hippocampus. Other investigators at the University of California, Irvine require TEm support for projects as diverse as bone, cartilage and lung development, immunocytochemistry of neuropeptides in the hippocampus and cerebral cortex, histochemical localization of peptidases and cholinesterases in the brain and spinal cord and studies on fibers within peripheral nerves. In addition, there are a number of other users with an equally broad variety of projects that require this TEM. The breadth of these projects from both major and minor users strongly underscores the many applications of TEM and the value of modern TEM facility for providing such services.